The development of dental techniques for replacing missing teeth included the installation of either permanent endosteal or subperiosteal anchor devices. Those implant devices were used for supporting an artificial tooth, crown, or a dental bridge.
Prior implant technology, incorporating endosteal root replacement, utilized a substantially planar member, such as a blade, loop, furcated stem, or similar element which was inserted within a prepared channel generally lying in a vertical plane with respect to the alveolar ridge. The planar member, when seated within this crypt, had an integral post projection above the bone on the ridge crest for accepting a dental prosthesis. That procedure was generally illustrated in U.S. Pat. Nos. 3,465,441 and 4,044,467.
A problem encountered with vertical placement was that precision cutting of the channel was required in order to assure sufficient confinement within the bone structure to prevent dislodgment. Another inherent shortcoming of the vertically oriented implant was that if an adequate amount of bone height or width was not present, such as proximate the shallow clearance under the maxillary sinus, the regions of the tuberosity, the mandibular nerve, or at similar anatomical landmarks, customized shapes or sizes were required; however, even those "special" implants presented accommodation problems. A further limitation was that the design of those vertical placed implants frequently included a sharp cutting edge and an impact force was required, such as through the application of a surgical mallet, for seating the implant into the osseous tissue. This often resulted in trauma to the bone. A further deficiency was that the anchorage was dependent upon frictional fit and not upon positive stabilization.
Previous attempts to avoid some of the above-referenced problems of the vertically positionable implants included use of horizontally oriented blade implants such as shown in U.S. Pat. No. 3,925,892. That implant device included a plate and post structure which necessitated surgically providing a horizontal groove as well as a vertical slot for reception of the post. A disadvantage of that procedure was that an additional surgical step was required for providing the vertical slot and, furthermore, difficulties were presented in locating the vertical slot such that the post and crown would be in alignment with the remaining teeth. Another deficiency of that procedure was that the vertical slot removed bone structure critically needed for resisting lateral forces as applied to the post during occlusal loading.
Still another method for securing a horizontal planar implant was shown in U.S. Pat. No. 3,919,772. That procedure, however, was limited to horizontal implants only and required the use of a dental jig for accurately drilling vertical bores in the jawbone such that a post could be inserted and properly aligned for mating with the horizontal blade.
Another problem in dental prosthesis, as previously encountered, was to provide reliable anchoring for long-term retention of the implant and for withstanding occlusive forces. The use of stabilizer bars, for example, had been applied to vertically oriented blade implants such as shown in U.S. Pat. No. 4,044,466. In order to locate the stabilizer bars, however, a positioning guide was required and, furthermore, this method was limited to vertical blade implants.
A still further anchoring arrangement applied a camming action as was illustrated in U.S. Pat. No. 4,177,562. That system also had its shortcomings in that its application was recommended for vertical insertion. The expandable retention was also dependent upon buccal-lingual dimension of the bone and the application of appropriate pressure so as not to traumatize or fracture the surrounding bone.
It should also be noted that the aforementioned implant devices were adapted for endosteal or within the bone embedment only whereas the instant invention further encompasses subperiosteal applications, i.e. placement on top of the bone tissue.
Although some devices have been previously employed for subperiosteal implantation, such as illustrated in British Pat. No. 770,696, the perforated mesh shown therein was not provided with apertures along its edges as in this invention. Further, the aforementioned implant devices did not encompass a modular assembly having separable components adapted for alternate interfitting arrangements.